| Abstrak/Abstract |
Phytophthora nicotianae is an important soil-borne pathogen in tropical, subtropical and temperate regions. To clarify the
genetic diversity of P. nicotianae and to understand its mode of transmission in Japan, we developed six new microsatellites
markers, consisting of six loci and 39 alleles. In a phylogenetic analysis, 138 isolates, including 125 from Japan and 13 from
overseas, were shown to differ, even though some were collected from the same host and location, suggesting that there is no
geographic or host plant clustering. Population structure analysis also revealed a highly admixed population of P. nicotianae
in Japan. Molecular analysis suggested high variance between individuals but no significant differences between populations.
Both A1 and A2 mating types were present in the same population, which could be due to high levels of variance between
individuals in the population. The absence of geographical structure between populations also suggests that the pathogen is
able to migrate from one population to another. We propose that this phenomenon could result from human activities related
to the transport of plant and associated agricultural materials.
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